The present invention relates to an energy management system applied at the time of operating energy equipment such as photovoltaic power generation facilities, a battery, and an electric water heater on a consumer end, and an energy management apparatus applied to the system and which is installed on a consumer or in the vicinity of the consumer.
Photovoltaic power generation facilities are assumed to be introduced and expanded in preparation for reduction in a load to global environment. However, the following is feared in cooperation and expansion to a power system of the photovoltaic power generation facilities. That is, due to a reverse power flow of photovoltaic generated power in a distribution system, a voltage rises up and a voltage control is influenced, or supply power of the entire system increases and a demand-and-supply balance control is influenced.
As one method of measures, a time zone of a thermal storage operation in an electric water heater installed on a consumer end is considered to be adjusted. Specifically, the electric water heater is operated such that a hot water is stored in a hot water storage tank by using cheaper electricity during a nighttime and the hot water is used during a daytime of the next day. When a photovoltaic power generation amount during a daytime of the next day is predicted to be large, a thermal storage operation during the nighttime of the previous day is suppressed and a thermal storable amount of the next day is increased. When the thermal storage operation is performed in conformity to a time zone at which a photovoltaic power generation amount during the daytime of the next day is large, a power demand is increased.
On the other hand, a reverse power flow in the above-described distribution system or an increase in a power supply of the entire system is considered to be reduced (see, for example, “Control Method for Reverse Power Flow of Photovoltaic Generation System-Operation Planning for Heat Pump Water Heater in accordance with Uncertainty Forecast-” Annual Conference of Power & Energy Society, IEE of Japan, August 2009).
The characteristics of the above-described method are summarized as follows. That is, when the above-described distribution voltage increase is caused by a power generation of the photovoltaic power generation during the daytime, the power generation amount is automatically suppressed by a voltage increase suppression function of the photovoltaic power generation facilities. However, the suppressed power generation amount can be effectively used by the thermal storage operation of the electric water heater. In general, a large amount of hot water is demanded by consumers also after the time zone at which power is generated during the daytime by the photovoltaic power generation facilities. Even if the thermal storage operation is moved as described above from the time zone of the nighttime of the previous day to the time zone at which power is generated during the daytime by the photovoltaic power generation facilities, a hot water is not short, and therefore, user-friendliness of the consumers is not impaired. Further, since the previously-installed electric water heater is used for the use of hot water, a special initial cost does not occur.